Wax-like fluorotelomer solids are described by Brady in U.S. Pat. No. 3,067,262. Such wax-like solids heretofore have been based predominantly on a fluorotelomer backbone of polytetrafluoroethylene (PTFE) formed by telomerization of tetrafluoroethylene (TFE) in trichlorotrifloroethane (TCTFE) in the presence of a peroxide free-radical initiator, with or without a so-called "Active Telogen" (chain transfer agent) to limit the molecular weight of the waxy telomer products, wherein TCTFE served both as a solvent and as a telogen. Telomerization can be defined as a reaction between two substances in which one substance provides the terminal groups (telogen) and the other provides the internal linkages of the telomer. An example is a free radical initiated reaction wherein an ethylenically unsaturated monomer, "A", reacts with a telogen, "YZ", to yield telomer: ##STR1##
In a preferred prior ate system, the monomer, "A", is tetrafluoroethylene (TFE), and the telogen, "YZ", is 1,1,2-trichloro-1,2,2-trifluoroethane (TCTFE). The resulting fluorotelomers are dispersed in TCTFE and, as such, provide waxy solid polymer dispersions that exhibit excellent dry lubricating properties which are used commercially.
However, chlorofluorocarbons, such as TCTFE, can be degraded in the presence of UV light to give chlorine free radicals which can react with ozone. Therefore, they are believed by some to be a major factor in the depletion of the protective ozone layer in the upper atmosphere. In addition, chlorofluorocarbons, such as TCTFE, may cause global warming. As a result of the widely perceived threat of certain CFC's to the ozone layer in the upper atmosphere and of their involvement in global warming, the manufacture and use of some CFC's, including TCTFE, will be banned in the future. Consequently, a replacement telogen/solvent must be found if production and use of versatile fluorotelomer dispersions are to continue. However, the chlorine content of CFC's would be expected to make them more active chain transfer agents (telogens) than chlorine-free fluorocarbons. It does not follow, therefore, that just any fluorine-containing organic carbon compounds can be substituted for CFC's as combined telogens/solvents. The challenge becomes that of finding substitute combined solvents/telogens that will allow the continued manufacture of fluorotelomer and their dispersions with no significant deviation in properties or performance in handling, manufacture, testing, and perceived quality.